Process optimization for dyeing silk fabric with dye extracted from Pyrus pashia (Wild Himalayan Pear) leaves
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Date
2020-02
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Pyrus pashia abundantly found across the Himalayas and also falls in the category of such kind of natural resources which are not economically beneficial and can be used to produce dye. In this study the leaves of Pyrus pashia were used to produce colour on silk fabric. Therefore present research work was carried out with the objectives to optimize extraction process for natural dye extracted from the leaves of Pyrus pashia, to optimize the dyeing and mordanting parameters for Pyrus pashia dye on silk fabric, to characterize the Pyrus pashia leaf dye using phytochemical analysis and FT-IR spectroscopy and to test the UPF and colour fastness properties of dyed silk fabric. Box-Behnken Design (RSM) was used for optimization of dyeing variables. Dye extraction medium, temperature and time were the constant parameters of the study. The independent variables of the study were dye material concentration, dyeing temperature and time, their interactive effects were assessed on dependent variables or responses like colour strength, warp and weft strength of dyed fabric, fastness to washing and rubbing. The optimized dyeing variables obtained for application of Pyrus pashia leaf dye extract on silk fabric were 5% (w/v) dye material concentration, 70°C dyeing temperature and 45 minutes dyeing time. Two natural (myrobalan and pomegranate rind) and two synthetic mordants (ferrous sulphate and alum) were used in the study. Mordanting variables like mordanting method, mordant concentration and mordanting time were optimized on the basis of higher colour strength. The overall colour fastness of control sample (dyed) was good. In case of washing, rubbing, acidic perspiration and dry cleaning the rating was ranged from slight colour change and staining (4) to negligible change in colour and staining (5). Moreover the fastness rating of alkaline perspiration was ranged from noticeable colour change (3-4) to slight to negligible colour change (4-5) and for light it was found in very good (6) range. The fastness rating was more or less remained same after mordanting with natural and synthetic mordants. Good UPF value was also reported after dyeing with Pyrus pashia leaf extract. Different phytochemicals such as terepenoids, glycoside, quinines, coumarins, anthocyanins, phenols and tannin were reported in the leaf extract of Pyrus pashia. The FT-IR spectroscopy provided evidences that IR spectrum of dye, undyed silk and dyed silk exhibited variation in their intensity and position of their absorption band. The optimized dyeing process was found to be environmentally safe because no harmful chemicals were used. Thus, optimized dyeing recipe can be recommended for use in small scale